The present invention relates to a lighting device or apparatus and, more particularly, to a lighting device using an optical waveguide emitting light laterally and adapted for multipurpose uses such as the illumination of signs and luminescing alphanumeric representations.
In general, a large segment of artificial lighting is done with neon lighting, particularly in those applications for lighting such as signs and luminescing writing. Despite its popularity for such applications, however, neon tubing is not a friendly material because it requires the use of transformers, is not readily transportable as the tubing readily breaks, and becomes significantly hot during use. The operating temperature of the tubing further limits its application to those environments permitting heat development. Moreover, the entire assembly of transformer, tubing, housing, and related accessories is heavy, further limiting the applications of the tubing to those instances permitting sufficiently strong, underlying structure to support the assembly. Additionally, the cost of tailoring a glass tube capable of being used in neon lighting is high, particularly in those applications where the tubing takes the shape of alpha/numeric or pictorial representations, and thus out of the economic reach of many potential customers and users who desire to have neon lighting in such shapes. The complexity and fragility of neon lighting systems, i.e., transformers and gas enclosing glass tubing, tend to exacerbate breakdowns of the systems, particularly in those more hostile environments.
There have been numerous attempts to develop lighting devices the emulated neon tubing over the years. The patent literature has several examples of these attempts. U.S. Pat. No. 4,891, 896 describes a simulated neon sign using raised translucent indicia stamped into an otherwise opaque plastic panel which is back lit by non-neon lighting. There is a further description of how the halo effect of neon lighting is simulated. U.S. Pat. No. 4,976,057 pertains to a simulated neon sign in which hollow tubes are made into the shape of letters and secured to a plastic panel. The panels are transparent in the area of the tubes and opaque in the other areas. Colored strips of translucent material may also be behind the tubes. A light source such as florescent tubing provides the light which is diffused into the tube to cause it to glow thereby simulating neon tubing. An alternate embodiment uses an array of light emitting diodes (LEDs) oriented in the shape of the tubes and positioned immediately behind the tubing to cause the tubing to glow. Still another more recent innovation to simulate neon tubing is found in U.S. Pat. No. 6,205,691 describing a lighting device comprising a transparent substrate that has grooves forming words or designs. The rearward facing side of the substrate is provided with a light blocking layer through which the grooves extend and a transparent layer over the light blocking layer and grooves. The grooves are roughened to provide a neon-like glow when the substrate is back lighted by any light source.
U.S. Pat. No. 5,537,297 describes a neon light substitute device comprising a curved transparent tube where both ends are enclosed in a housing. A light source is positioned adjacent the end and an opaque strip is placed along the length of the exposed portion of the transparent tube covering a minor portion of the circumference of the tube. According to the patent, light shining into the tube is partially reflected out of the side wall of the tube, thus emulating neon lighting. A later issued patent U.S. Pat. No. 6,123,442, describes the use of an optical waveguide or large diameter light fibers using a diffuse light reflecting material around a portion of the light fiber to cause light to exit in a desired direction transverse to the axis of the fiber. The patent also discusses of the use of the light fibers in the form of alphanumeric symbols illuminated by the diffuse light and illustrates this in FIGS. 6, 7, and 8.
Despite the attempts of simulating neon lighting by those in the prior art, the efforts have fallen short of solving the triple, dilemmas of complexity, size, and environmental adaptability. There still remains a severe need for technology that will provide economic and friendly lighting devices and are ready substitutes for neon lighting. It is therefore a paramount object of the present invention to provide a superior alternative to present neon and neon-like lighting devices, both in cost and application, through the use of high intensity light sources such as high intensity LEDs coupled with optical wave guides for various signage and display applications. It is still another significant object of the present invention to provide for a lighting device that is easily adapted for use with signage and other alphanumeric/pictorial representations for various decorative, consumer, commercial, architectural, and other uses. Still another important object of the present invention is to provide a lighting device that avoids complexities such as the use of transformers, glass tubing, and heavy support structures necessary for neon lighting devices. Yet another object of the present invention is to provide for a lighting device that is easily fabricated, uses light weight materials largely break proof, and flexible in manufacturing to be formed into various desired shapes at economical costs. Yet another important object of the present invention is to provide for a lighting device that can be readily fabricated for customer specific purposes while maintaining optimal performance and economics of manufacture. These and other important objects of the present invention are addressed by the ensuing detailed description and appended drawings.
In accordance with one embodiment of the present invention, an illumination device comprises at least one housing, at least one high intensity light emitting diode (LED) positioned within the housing, an optical waveguide of predetermined length having one end secured to said housing with an end surface adjacent to said LED so that light emitted from the LED enters into the waveguide through the end surface, and having a surface area of the waveguide intermediate the end surfaces thereof optically treated so as cause a portion of the light incident upon the surface area to be reflected out of the waveguide through a second surface area located intermediate the end surface thereof. The waveguide may also be rotatable relative to the housing so as to change the direction of the light through the second surface area. Additionally, in accordance with a further preferred embodiment of the present invention, indicia may be placed within or near the first surface area and illuminated so as to be reflected out or at least visible through the second surface area.